Method for preparing anisotropic samarium-iron-nitrogen magnetic powder

Abstract

The invention discloses a method for preparing anisotropic samarium-iron-nitrogen magnetic powder, and belongs to the technical field of magnetic materials, the method comprises the following steps: preparing Sm and Fe according to design components, and smelting to obtain samarium-iron alloy molten steel; casting the samarium-iron alloy molten steel onto a cooling roller to obtain an iron-samarium alloy sheet; the iron-samarium alloy sheet is placed in a vacuum heat treatment furnace to be subjected to homogenization treatment, the alloy sheet obtained after homogenization treatment is cooled to 200-300 DEG C, in the vacuum environment, hydrogen is introduced into the furnace, the absolute pressure of the hydrogen is controlled to be 0.05-0.1 MPa, and hydrogenation treatment is conducted for 2 h; after hydrogenation is completed, the temperature is increased to 400 DEG C, nitrogen is introduced to 0.5 MPa, the temperature is increased to 530 DEG C, then the furnace temperature is reduced to the room temperature, and the anisotropic samarium-iron-nitrogen magnetic powder is obtained.The preparation method of the samarium-iron-nitrogen magnetic powder has the advantages of being simple in preparation process, low in energy consumption, high in production efficiency, small in magnetic powder particle size, high in magnetic performance and good in magnetocrystalline anisotropy.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic materials, and in particular relates to a method for preparing anisotropic samarium iron nitrogen magnetic powder. Background Art

[0002] In the field of magnetic materials, samarium iron nitrogen (Sm2Fe 17 N x ) Magnetic powder is an important functional material, which is widely used in various magnetic components, such as motors, magnetic data lines, induction magnetic rings, etc. The preparation methods of SmFeN magnetic powder mainly include HDDR (hydrogenation-disproportionation-dehydrogenation-rehydrogenation) method, melt rapid quenching method and reduction diffusion method.

[0003] In the field of powder metallurgy, the particle size, shape and magnetic properties of magnetic powder are key factors affecting the performance of magnetic components. In the field of material processing, the preparation process of magnetic powder needs to consider factors such as energy consumption, production efficiency and environmental protection.

[0004] The HDDR method is a traditional preparation method. Through the process of hydrogenation, disproportionation, dehydrogenation and rehydrogenation, the samarium iron alloy can undergo phase transformation to form samarium iron nitrogen magnetic powder with high magnetocrystalline anisotropy. For example, the Chinese patent application with publication number CN118969491A provides a method for preparing isotropic samarium iron nitrogen magnetic powder, including the following steps: 17 The invention discloses a method for preparing a samarium iron alloy by mixing the metal Sm and Fe with a Sm excess of 5% to 10%, and then melting and rapidly solidifying the metal Sm2Fe alloy flakes; crushing the Sm2Fe alloy flakes to prepare a powdered Sm2Fe alloy; performing HDDR treatment on the powdered Sm2Fe alloy to obtain an isotropic alloy block; crushing the isotropic alloy block, and performing aging treatment to obtain an isotropic alloy powder; performing high temperature nitriding treatment on the isotropic alloy powder after aging treatment to obtain Sm2Fe 17 N3 isotropic magnetic powder, the prepared isotropic samarium iron nitrogen magnetic powder has both high magnetic energy product and coercive force.

[0005] Another example is a Chinese patent application with publication number CN117912795A which provides a Sm2Fe 17 The in-situ multi-stage preparation method of N3 magnetic powder relates to the technical field of magnetic material preparation. It comprises the following steps: (1) in a protective atmosphere, a samarium iron alloy flake is obtained by an induction melting and rapid solidification method; (2) a samarium iron alloy flake with good oxidation resistance is added to a reactor, and the samarium iron alloy flake is crushed into powder by hydrogenation and dehydrogenation based on the principle of hydrogen absorption and disproportionation decomposition; (3) a high-pressure nitrogen is filled into the reactor, and the samarium iron alloy powder is subjected to in-situ nitridation treatment to obtain Sm2Fe 17 N3 magnetic powder.

[0006] There are some problems with the existing methods for preparing SmFeN magnetic powder. The HDDR method has complex process, high energy consumption, low production efficiency, and is not suitable for large-scale production; the high-pressure hydrogen pyrolysis method requires high-pressure equipment, large equipment investment, complex operation, and is also not suitable for large-scale production; therefore, how to develop a method for preparing SmFeN magnetic powder with a simple preparation process, low energy consumption, high production efficiency, small magnetic powder particle size, high magnetic properties and good magnetic crystal anisotropy is the main problem facing current technology. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing anisotropic samarium iron nitrogen magnetic powder, so as to solve the problems of high energy consumption and complex process in the prior art for preparing samarium iron nitrogen magnetic powder.

[0008] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing anisotropic samarium iron nitrogen magnetic powder comprises the following steps: Step 1, preparing Sm and Fe, smelting, and obtaining samarium-iron alloy steel liquid; Step 2, casting the samarium-iron alloy steel liquid onto a cooling roller to obtain an iron-samarium alloy sheet; Step 3, placing the iron-samarium alloy sheet in a vacuum heat treatment furnace for homogenization treatment, cooling the alloy sheet after homogenization treatment to 200-300° C., introducing hydrogen into the furnace under vacuum environment, controlling the absolute pressure of hydrogen at 0.05-0.1 MPa, and hydrogenating for 2 hours; Step 4: After the hydrogenation is completed, the temperature is raised to 400° C., nitrogen is charged to 0.5 MPa, the temperature is raised to 530° C., and then the furnace temperature is lowered to room temperature to obtain the anisotropic samarium iron nitrogen magnetic powder.

[0009] Furthermore, the specific operations of step 1 are as follows: Prepare Sm and Fe, add 50% Sm and all Fe by total mass into a smelting furnace, evacuate the interior of the smelting furnace, raise the temperature until Sm and Fe melt into liquid state, then add the remaining Sm, continue smelting for 40 minutes after it is completely melted, and obtain samarium-iron alloy steel liquid.

[0010] The present invention adopts a secondary feeding method to carry out rapid solidification smelting, and after homogenization treatment, Sm2Fe 17 The alloy sheet is different from the complicated processes of the HDDR method and the high pressure method. The preparation process of the alloy sheet of the present invention is simpler, has low energy consumption, high production efficiency, and is suitable for large-scale production.

[0011] Furthermore, in the step 4, the heating rate during the process of heating to 400° C. is 10° C. / min.

[0012] Furthermore, the atomic percentage of Sm and Fe in step 1 is Sm 2.2 Fe 17, and then convert the atomic percentage into mass percentage; which is consistent with the theoretical alloy composition Sm2Fe 17 In comparison, Sm is in excess of 10%.

[0013] Furthermore, in step 1, Sm is samarium particles with a particle size of 1 to 100 mm and a purity of ≥99.9%.

[0014] Furthermore, in step 1, Fe is an iron rod with a purity of ≥99%.

[0015] Furthermore, in step 1, the internal pressure of the smelting furnace is ≤10Pa.

[0016] Furthermore, in step 2, the rotation speed of the cooling roller is 2 r / min.

[0017] Furthermore, the homogenization pressure in step 3 is 1×10 -2 Pa, temperature is 1000℃, time is 8h.

[0018] Furthermore, in step 4, the average particle size of the anisotropic samarium iron nitrogen magnetic powder is 20 μm.

[0019] Furthermore, the method for preparing anisotropic samarium iron nitrogen magnetic powder also includes a testing step of the anisotropic samarium iron nitrogen magnetic powder, and the testing step is as follows: The anisotropic samarium iron nitrogen magnetic powder and polyvinyl chloride (CPE) are mixed in a mass ratio of 10:90, and then the mixture is placed in a calender for calendering. The calendering temperature is 180°C, the calendering pressure is 10MPa, and the calendering time is 5min. After the calendering is completed, the obtained magnetic sheet is taken out, and the surface magnetism of the magnetic sheet is tested after the magnetic sheet is magnetized.

[0020] Beneficial effects of the present invention: 1. Reduce energy consumption: The present invention only adopts low-temperature negative pressure hydrogen decomposition method to obtain magnetic powder with an average particle size of 20 μm, without dehydrogenation treatment. Compared with the HDDR method and the high-pressure method, the present invention has small equipment investment and greatly reduced energy consumption, which is beneficial to saving energy and reducing production costs.

[0021] 2. Improve production efficiency: The nitriding process of the present invention adopts a continuous slow heating method, which is different from the traditional segmented insulation method. It improves the activity of nitrogen atoms, makes the nitriding process easier to carry out, and has a higher nitrogen content, thereby improving production efficiency.

[0022] 3. Improvement of magnetic powder performance: The magnetic sheets prepared from the anisotropic samarium iron nitrogen magnetic powder provided by the preparation method of the present invention have higher magnetic properties, which is beneficial to improving the performance of the prepared magnetic components.

[0023] In summary, the present invention provides a method for preparing samarium iron nitrogen magnetic powder. Compared with the prior art, the present invention has the advantages of simple preparation process, low energy consumption, high production efficiency, small magnetic powder particle size, high magnetic properties and good magnetic crystal anisotropy. It is an ideal method for preparing samarium iron nitrogen magnetic powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] Figure 1 This is a graph showing the change of temperature over time in a method for preparing anisotropic samarium iron nitrogen magnetic powder in Example 1 of the present invention; Figure 2 This is a graph showing the change of pressure over time in a method for preparing anisotropic samarium iron nitrogen magnetic powder in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0027] The terms used in the embodiments of the present application are only for the purpose of describing specific implementation rules, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the implementation rules of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0028] It should be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation regulations of this application.

[0029] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0030] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0032] The present invention provides a method for preparing anisotropic samarium iron nitrogen magnetic powder, comprising the following steps: Step 1, preparing Sm and Fe, smelting, and obtaining samarium-iron alloy steel liquid; Step 2, casting the samarium-iron alloy steel liquid onto a cooling roller to obtain an iron-samarium alloy sheet; Step 3, placing the iron-samarium alloy sheet in a vacuum heat treatment furnace for homogenization treatment, cooling the alloy sheet after homogenization treatment to 200-300° C., introducing hydrogen into the furnace under vacuum environment, controlling the absolute pressure of hydrogen at 0.05-0.1 MPa, and hydrogenating for 2 hours; Step 4: After the hydrogenation is completed, the temperature is raised to 400° C., nitrogen is charged to 0.5 MPa, the temperature is raised to 530° C., and then the furnace temperature is lowered to room temperature to obtain the anisotropic samarium iron nitrogen magnetic powder.

[0033] In some embodiments, the specific operations of step 1 are as follows: Prepare Sm and Fe, add 50% Sm and all Fe by total mass into a smelting furnace, evacuate the interior of the smelting furnace, raise the temperature until Sm and Fe melt into liquid state, then add the remaining Sm, continue smelting for 40 minutes after it is completely melted, and obtain samarium-iron alloy steel liquid.

[0034] In some embodiments, the heating rate during the heating to 400° C. in step 4 is 10° C. / min.

[0035] In some embodiments, the atomic percentage of Sm and Fe in step 1 is Sm 2.2 Fe 17 , and then convert the atomic percentage into mass percentage; which is consistent with the theoretical alloy composition Sm2Fe 17 In comparison, Sm is in excess of 10%.

[0036] In some embodiments, Sm in step 1 is samarium particles with a particle size of 1 to 100 mm and a purity of ≥99.9%.

[0037] In some embodiments, in step 1, Fe is an iron rod with a purity of ≥99%.

[0038] In some embodiments, in step 1, the internal pressure of the smelting furnace is ≤10Pa.

[0039] In some embodiments, the cooling roller rotation speed in step 2 is 2 r / min.

[0040] In some embodiments, the homogenization pressure in step 3 is 1×10-2 Pa, temperature is 1000℃, time is 8h.

[0041] In some embodiments, the average particle size of the anisotropic SmFeN magnetic powder in step 4 is 20 μm.

[0042] In some embodiments, the method for preparing anisotropic samarium iron nitrogen magnetic powder further includes a testing step of the anisotropic samarium iron nitrogen magnetic powder, and the testing step is as follows: The anisotropic samarium iron nitrogen magnetic powder and polyvinyl chloride (CPE) are mixed in a mass ratio of 10:90, and then the mixture is placed in a calender for calendering. The calendering temperature is 180°C, the calendering pressure is 10MPa, and the calendering time is 5min. After the calendering is completed, the obtained magnetic sheet is taken out, and the surface magnetism of the magnetic sheet is tested after the magnetic sheet is magnetized.

[0043] The following is further described in conjunction with specific embodiments.

[0044] Example 1

[0045] See also Figure 1-Figure 2 , a method for preparing anisotropic samarium iron nitrogen magnetic powder, comprising the following steps: Step 1. Press Sm 2.2 Fe 17 Prepare the raw materials by atomic percentage. Fe is selected as an iron rod with a purity of 99%, and Sm is selected as metal samarium particles with a purity of 99.9%. The particle size of the metal samarium particles is 1 to 10 mm, which is consistent with the theoretical alloy composition Sm2Fe 17 In comparison, the excess of Sm is 10%, with 75.95 kg of iron rod and 26.45 kg of samarium pellets; Step 2, add 50% Sm and all Fe of the weighed raw materials into the smelting furnace, put the remaining Sm into the secondary feeding silo, pump the smelting furnace to 10Pa, heat until Sm and Fe melt into liquid, then add the remaining Sm, completely melt and continue smelting for 40 minutes, measure the temperature of the samarium-iron alloy steel liquid and record it in Table 1; Step 3: The samarium-iron alloy steel liquid is poured onto a cooling roller through a tundish and a runner. The speed of the cooling roller is 2 r / min, so that the samarium-iron alloy steel liquid forms Sm2Fe 17 phase, and falls onto the water cooling plate below, and is cooled to room temperature to obtain iron-samarium alloy flakes; Step 4: Place the iron-samarium alloy sheet in a vacuum heat treatment furnace and evacuate to 1×10 -2 Pa, heat to 1000℃, keep warm for 8h, and stop heating; Step 5, cooling to 260°C and keeping warm, introducing hydrogen into a vacuum heat treatment furnace under vacuum environment, the absolute pressure of hydrogen is controlled at 0.08MPa, and the hydrogenation time is 2h; Step 6: After the hydrogenation is completed, the temperature is raised to 400°C at a heating rate of 10°C / min, nitrogen is charged to 0.5MPa, and then the temperature is raised to 530°C at a heating rate of 0.2°C / min, and then the furnace temperature is lowered to room temperature to obtain anisotropic samarium iron nitrogen magnetic powder with an average particle size of 20μm; Step 7, mix the anisotropic samarium iron nitrogen magnetic powder and polyvinyl chloride (CPE) in a mass ratio of 10:90, and then put the mixture into a calender for calendering. The calendering temperature is 180°C, the calendering pressure is 10MPa, and the calendering time is 5min. After the calendering is completed, take out the magnetic sheet with a thickness of 0.4mm, magnetize the magnetic sheet, and test the surface magnetism of the magnetic sheet, and record the test results in Table 1.

[0046] Example 2

[0047] A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that the "cooling to 260° C. and keeping warm" in step 5 of Example 1 is adjusted to "cooling to 200° C. and keeping warm".

[0048] Example 3

[0049] A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that the "cooling to 260° C. and keeping warm" in step 5 of Example 1 is adjusted to "cooling to 300° C. and keeping warm".

[0050] Example 4

[0051] A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that "the absolute pressure of hydrogen is controlled at 0.08 MPa" in step 5 of Example 1 is adjusted to "the absolute pressure of hydrogen is controlled at 0.05 MPa".

[0052] Example 5

[0053] A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that "the absolute pressure of hydrogen is controlled at 0.08 MPa" in step 5 of Example 1 is adjusted to "the absolute pressure of hydrogen is controlled at 0.1 MPa".

[0054] Example 6

[0055] A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that the "then heat up to 530°C at a heating rate of 0.2°C / min" in step 6 of Example 1 is adjusted to "then heat up to 530°C at a heating rate of 0.1°C / min".

[0056] Example 7

[0057] A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that the "then heat up to 530°C at a heating rate of 0.2°C / min" in step 6 of Example 1 is adjusted to "then heat up to 530°C at a heating rate of 0.5°C / min".

[0058] Example 8

[0059] A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that the "taking out the magnetic sheet with a thickness of 0.4 mm" in step 6 of Example 1 is adjusted to "taking out the magnetic sheet with a thickness of 0.3 mm".

[0060] Example 9

[0061] A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that the "taking out the magnetic sheet with a thickness of 0.4 mm" in step 6 of Example 1 is adjusted to "taking out the magnetic sheet with a thickness of 0.5 mm".

[0062] Comparative Example 1 A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that the "cooling to 260° C. and keeping warm" in step 5 of Example 1 is adjusted to "cooling to 150° C. and keeping warm".

[0063] Comparative Example 2 A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that "the absolute pressure of hydrogen is controlled at 0.08 MPa" in step 5 of Example 1 is adjusted to "the absolute pressure of hydrogen is controlled at 0.01 MPa".

[0064] Comparative Example 3 A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that the "then heat the temperature to 530°C at a heating rate of 0.5°C / min" in step 6 of Example 1 is adjusted to "then heat the temperature to 530°C at a heating rate of 5°C / min".

[0065] Comparative Example 4 A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that step 6 in Example 1 is adjusted, and the operation of step 6 in this comparative example is: After the hydrogenation is completed, the temperature is raised to 400°C at a heating rate of 10°C / min, and nitrogen is filled to 0.5MPa. After keeping warm for 0.5h, the temperature is raised to 450°C after 10min, and after keeping warm for 3h, the temperature is raised to 530°C after 10min. After keeping warm for 5h, the heating is terminated, and the furnace temperature is then lowered to room temperature to obtain anisotropic samarium iron nitrogen magnetic powder.

[0066] Comparative Example 5 A method for preparing anisotropic samarium iron nitrogen magnetic powder, compared with Example 1, the only difference is that a dehydrogenation step is added, that is, step 6 of Example 1 is adjusted, and the operation of step 6 in this comparative example is: The temperature was raised to 400°C at a heating rate of 10°C / min, and dehydrogenation was carried out after keeping the temperature for 30 minutes. After the dehydrogenation was completed, the vacuum was evacuated to below 1Pa, and nitrogen was filled to 0.5MPa. Then, the temperature was raised to 530°C at a heating rate of 0.2°C / min, and the furnace temperature was then lowered to room temperature to obtain anisotropic samarium iron nitrogen magnetic powder with an average particle size of 20μm.

[0067] The magnetic sheets obtained from Examples 1 to 9 and Comparative Examples 1 to 5 were tested. The thickness of the magnetic sheets was measured using a vernier caliper, and the surface magnetism was measured using a FE-103 Gaussmeter. The results are recorded in Table 1.

[0068] Table 1

[0069] From the analysis of the data in Table 1, it can be seen that the magnetic sheets prepared from the samarium iron nitrogen magnetic powder obtained in Examples 1 to 9 have a thickness of 0.3-0.5 mm and a surface magnetism of 960-1230 Gs, and have good magnetic properties.

[0070] Specifically, it can be seen from the test results in Example 1, Example 2, Example 3 and Comparative Example 1 that the higher the hydrogen fracture temperature, the finer the alloy sheets are broken into magnetic powder during the hydrogen fracture process, the better the nitriding effect is in the subsequent nitriding process, the higher the nitrogen content of the magnetic powder, and thus the higher the magnetic properties. After being made into magnetic sheets, the magnetic sheets have higher surface magnetism.

[0071] It can be seen from the test results in Example 1, Example 4, Example 5 and Comparative Example 2 that the higher the hydrogen fracture pressure, the more hydrogen the alloy sheet absorbs during the hydrogen fracture process, and the more nitrogen absorbed during the subsequent nitridation process, and the higher the nitrogen content of the magnetic powder, thereby having higher magnetic properties. After being made into a magnetic sheet, it has a higher surface magnetism.

[0072] It can be seen from the test results of Example 1, Example 6, Example 7 and Comparative Example 3 that during the nitriding process, the slower the heating rate, the better the nitriding effect, the higher the performance of the magnetic powder, and thus the higher the surface magnetism.

[0073] It can be seen from the test results in Example 1 and Comparative Example 4 that slow heating has better magnetic properties than step heating, because the activity of nitrogen also increases slowly during the slow heating process, and the nitriding effect is better.

[0074] It can be seen from the test results in Example 1 and Comparative Example 5 that no dehydrogenation treatment is better than dehydrogenation treatment. Without dehydrogenation, hydrogen atoms will open channels for nitrogen atoms to penetrate, making nitriding easier. After dehydrogenation, there will be no such channels, and the nitriding process will be more difficult to carry out. The nitriding effect is not good, resulting in reduced performance.

[0075] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0076] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing anisotropic samarium iron nitrogen magnetic powder, characterized in that: The following steps are involved: Step 1, preparing Sm and Fe, smelting, and obtaining samarium-iron alloy steel liquid; Step 2, casting the samarium-iron alloy steel liquid onto a cooling roller to obtain an iron-samarium alloy sheet; Step 3, placing the iron-samarium alloy sheet in a vacuum heat treatment furnace for homogenization treatment, cooling the alloy sheet after homogenization treatment to 200-300° C., introducing hydrogen into the furnace under vacuum environment, controlling the absolute pressure of hydrogen at 0.05-0.1 MPa, and hydrogenating for 2 hours; Step 4: After the hydrogenation is completed, the temperature is raised to 400° C., nitrogen is charged to 0.5 MPa, the temperature is raised to 530° C., and then the furnace temperature is lowered to room temperature to obtain the anisotropic samarium iron nitrogen magnetic powder.

2. The method for preparing anisotropic samarium iron nitrogen magnetic powder according to claim 1, characterized in that: After nitrogen is filled in step 4, the heating rate is 0.1-0.5°C / min.

3. The method for preparing anisotropic samarium iron nitrogen magnetic powder according to claim 1, characterized in that: Step 1: Prepare Sm and Fe, add 50% Sm and all Fe by total mass into a smelting furnace, evacuate the interior of the smelting furnace, raise the temperature until Sm and Fe melt into liquid state, then add the remaining Sm, continue smelting for 40 minutes after it is completely melted, and obtain samarium-iron alloy steel liquid.

4. The method for preparing anisotropic samarium iron nitrogen magnetic powder according to claim 3, characterized in that: In step 1, the atomic percentage of Sm and Fe is Sm 2.2 Fe 17 .

5. The method for preparing anisotropic samarium iron nitrogen magnetic powder according to claim 3, characterized in that: The internal pressure of the smelting furnace is ≤10Pa.

6. The method for preparing anisotropic samarium iron nitrogen magnetic powder according to claim 1, characterized in that: The homogenization pressure in step 3 is 1×10 -2 Pa, temperature is 1000℃, time is 8h.

7. The method for preparing anisotropic samarium iron nitrogen magnetic powder according to claim 1, characterized in that: The average particle size of the anisotropic samarium iron nitrogen magnetic powder in step 4 is 20 μm.

8. The method for preparing anisotropic samarium iron nitrogen magnetic powder according to claim 1, characterized in that: The test steps of anisotropic samarium iron nitrogen magnetic powder are also included, and the test steps are as follows: Anisotropic samarium iron nitrogen magnetic powder and polyvinyl chloride are mixed, and then the mixture is put into a calender for calendering. After the calendering is completed, the obtained magnetic sheet is taken out, and the surface magnetism of the magnetic sheet is tested after the magnetic sheet is magnetized.

9. The method for preparing anisotropic samarium iron nitrogen magnetic powder according to claim 8, characterized in that: The mass ratio of anisotropic SmFeN magnetic powder to polyvinyl chloride is 10:

90.

10. The method for preparing anisotropic samarium iron nitrogen magnetic powder according to claim 8, characterized in that: The calendering temperature is 180°C, the calendering pressure is 10MPa, and the calendering time is 5min.

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